Changes in concentrations of NMDA receptor subunit GluN2B, Arc and syntaxin-1 in dorsal hippocampus Schaffer collateral synapses in a rat learned helplessness model of depression

Major depressive disorder involves changes in synaptic structure and function, but the molecular underpinnings of these changes are still not established. In an initial pilot experiment, whole-brain synaptosome screening with quantitative western blotting was performed to identify synaptic proteins that may show concentration changes in a congenital rat learned helplessness model of depression. We found that the N-methyl-d-aspartate receptor (NMDAR) subunits GluN2A/GluN2B, activity-regulated cytoskeleton-associated protein (Arc) and syntaxin-1 showed significant concentration differences between congenitally learned helpless (LH) and nonlearned helpless (NLH) rats. Having identified these three proteins, we then performed more elaborate quantitative immunogold electron microscopic analyses of the proteins in a specific synapse type in the dorsal hippocampus: the Schaffer collateral synapse in the CA1 region. We expanded the setup to include also unstressed wild-type (WT) rats. The concentrations of the proteins in the LH and NLH groups were compared to WT animals. In this specific synapse, we found that the concentration of NMDARs was increased in postsynaptic spines in both LH and NLH rats. The concentration of Arc was significantly increased in postsynaptic densities in LH animals as well as in presynaptic cytoplasm of NLH rats. The concentration of syntaxin-1 was significantly increased in both presynaptic terminals and postsynaptic spines in LH animals, while pre- and postsynaptic syntaxin-1 concentrations were significantly decreased in NLH animals. These protein changes suggest pathways by which synaptic plasticity may be increased in dorsal hippocampal Schaffer collateral synapses during depression, corresponding to decreased synaptic stability.

Combination of amisulpride and olanzapine in treatment-resistant schizophrenic psychoses

Treatment-resistant schizophrenia often leads to combined application of antipsychotic drugs. We report first experience with the combination of olanzapine and amisulpride. Improvement of psychopathological state and side effects could be achieved, and drug doses were lower than under monotherapy. We thus conclude that this approach represents a useful therapeutic option.

Clinical Trial of the Potassium Channel Activator Diazoxide for Major Depressive Disorder Halted Due to Intolerability

BACKGROUND

Some glutamatergic modulators have demonstrated rapid and relatively sustained antidepressant properties in patients with major depressive disorder. Because the potassium channel activator diazoxide increases glutamate uptake via potassium channel activation, we hypothesized that it might exert antidepressant effects by increasing the removal of glutamate from the synaptic cleft, thereby reducing excessive glutamate transmission.

METHODS

This randomized, double-blind, placebo-controlled, crossover, single-site inpatient clinical study was conducted at the National Institute of Mental Health to assess the efficacy and safety of a 3-week course of diazoxide (200-400 mg daily, twice a day) versus a 3-week course of placebo in 6 participants with treatment-refractory major depressive disorder. The primary clinical outcome measure was change in Montgomery-Asberg Depression Rating Scale score from baseline to posttreatment. Quantitative insulin sensitivity check index, as well as concomitant imaging measures (electroencephalography, proton magnetic resonance spectroscopy, magnetoencephalography), were used as potential surrogate markers of target (KATP channel) engagement.

RESULTS

The study was halted due to severe adverse effects. Given the small sample size, statistical evaluation of the effect of diazoxide on Montgomery-Asberg Depression Rating Scale scores or the imaging measures was not pursued. Visual inspection of the quantitative insulin sensitivity check index test revealed no evidence of target engagement.

CONCLUSIONS

Although the results are negative, they are an important addition to the literature in this rapidly changing field.

Whole-Brain Mapping of Neuronal Activity in the Learned Helplessness Model of Depression

Some individuals are resilient, whereas others succumb to despair in repeated stressful situations. The neurobiological mechanisms underlying such divergent behavioral responses remain unclear. Here, we employed an automated method for mapping neuronal activity in search of signatures of stress responses in the entire mouse brain. We used serial two-photon tomography to detect expression of c-FosGFP - a marker of neuronal activation - in c-fosGFP transgenic mice subjected to the learned helplessness (LH) procedure, a widely used model of stress-induced depression-like phenotype in laboratory animals. We found that mice showing "helpless" behavior had an overall brain-wide reduction in the level of neuronal activation compared with mice showing "resilient" behavior, with the exception of a few brain areas, including the locus coeruleus, that were more activated in the helpless mice. In addition, the helpless mice showed a strong trend of having higher similarity in whole-brain activity profile among individuals, suggesting that helplessness is represented by a more stereotypic brain-wide activation pattern. This latter effect was confirmed in rats subjected to the LH procedure, using 2-deoxy-2[18F]fluoro-D-glucose positron emission tomography to assess neural activity. Our findings reveal distinct brain activity markings that correlate with adaptive and maladaptive behavioral responses to stress, and provide a framework for further studies investigating the contribution of specific brain regions to maladaptive stress responses.

Increased metabolic activity in the septum and habenula during stress is linked to subsequent expression of learned helplessness behavior

Uncontrollable stress can have a profound effect on an organism's ability to respond effectively to future stressful situations. Behavior subsequent to uncontrollable stress can vary greatly between individuals, falling on a spectrum between healthy resilience and maladaptive learned helplessness. It is unclear whether dysfunctional brain activity during uncontrollable stress is associated with vulnerability to learned helplessness; therefore, we measured metabolic activity during uncontrollable stress that correlated with ensuing inability to escape future stressors. We took advantage of small animal positron emission tomography (PET) and 2-deoxy-2[(18)F]fluoro-D-glucose ((18)FDG) to probe in vivo metabolic activity in wild type Sprague Dawley rats during uncontrollable, inescapable, unpredictable foot-shock stress, and subsequently tested the animals response to controllable, escapable, predictable foot-shock stress. When we correlated metabolic activity during the uncontrollable stress with consequent behavioral outcomes, we found that the degree to which animals failed to escape the foot-shock correlated with increased metabolic activity in the lateral septum and habenula. When used a seed region, metabolic activity in the habenula correlated with activity in the lateral septum, hypothalamus, medial thalamus, mammillary nuclei, ventral tegmental area, central gray, interpeduncular nuclei, periaqueductal gray, dorsal raphe, and rostromedial tegmental nucleus, caudal linear raphe, and subiculum transition area. Furthermore, the lateral septum correlated with metabolic activity in the preoptic area, medial thalamus, habenula, interpeduncular nuclei, periaqueductal gray, dorsal raphe, and caudal linear raphe. Together, our data suggest a group of brain regions involved in sensitivity to uncontrollable stress involving the lateral septum and habenula.

Synaptic abnormalities in the infralimbic cortex of a model of congenital depression

Multiple lines of evidence suggest that disturbances in excitatory transmission contribute to depression. Whether these defects involve the number, size, or composition of glutamatergic contacts is unclear. This study used recently introduced procedures for fluorescence deconvolution tomography in a well-studied rat model of congenital depression to characterize excitatory synapses in layer I of infralimbic cortex, a region involved in mood disorders, and of primary somatosensory cortex. Three groups were studied: (1) rats bred for learned helplessness (cLH); (2) rats resistant to learned helplessness (cNLH); and (3) control Sprague Dawley rats. In fields within infralimbic cortex, cLH rats had the same numerical density of synapses, immunolabeled for either the postsynaptic density (PSD) marker PSD95 or the presynaptic protein synaptophysin, as controls. However, PSD95 immunolabeling intensities were substantially lower in cLH rats, as were numerical densities of synapse-sized clusters of the AMPA receptor subunit GluA1. Similar but less pronounced differences (comparable numerical densities but reduced immunolabeling intensity for PSD95) were found in the somatosensory cortex. In contrast, non-helpless rats had 25% more PSDs than either cLH or control rats without any increase in synaptophysin-labeled terminal frequency. Compared with controls, both cLH and cNLH rats had fewer GABAergic contacts. These results indicate that congenital tendencies that increase or decrease depression-like behavior differentially affect excitatory synapses.

Diffusion weighted MRI in the early phase after electroconvulsive therapy

Although cognitive side effects may occur after electroconvulsive therapy (ECT), no structural brain abnormalities have been detected after ECT with conventional magnetic resonance imaging (MRI). Transient disturbances of memory function are common findings after ECT indicating functional compromise. Diffusion weighted imaging (DWI) has been shown to be sensitive to focal tissue changes associated with compromise of energy metabolism in cerebral ischemia and after prolonged ictal activity. We used conventional MRI and DWI in an exploratory study examining ten patients after treatment with ECT, eight of whom experienced short-lasting memory disturbances. MRI and DWI showed no definite signal abnormalities on qualitative and quantitative analysis. In three patients, equivocal marginal DWI hyperintensity was noted in the hippocampal formation. These findings are in line with previous negative studies using conventional MRI. Higher resolution DWI and serial imaging may be necessary to visualize possible minimal signal changes after ECT.

Beyond Depression: Towards a Process-Based Approach to Research, Diagnosis, and Treatment

Despite decades of research on the etiology and treatment of depression, a significant proportion of the population is affected by the disorder, fails to respond to treatment and is plagued by relapse. Six prominent scientists, Aaron Beck, Richard Davidson, Fritz Henn, Steven Maier, Helen Mayberg, and Martin Seligman, gathered to discuss the current state of scientific knowledge on depression, and in particular on the basic neurobiological and psychopathological processes at play in the disorder. These general themes were addressed: 1) the relevance of learned helplessness as a basic process involved in the development of depression; 2) the limitations of our current taxonomy of psychological disorders; 3) the need to work towards a psychobiological process-based taxonomy; and 4) the clinical implications of implementing such a process-based taxonomy.

Cyclic AMP response element-binding protein and depression

Depression is one of the most common and most devastating psychiatric disorders. Although a variety of treatment strategies is available, a major problem in its therapy consists of the unpredictability of the drug response. Furthermore, most antidepressant drugs, which usually increase 5-HT and norepinephrine levels in the synaptic cleft, are likely to produce side effects. Therefore, the quest for new options in antidepressant treatment is urgent. A novel therapeutic approach beyond manipulating the neurotransmitter-receptor interaction consists of targeting signal transduction and gene expression pathways. One of the best investigated pathways is the cyclic AMP second messenger system which ultimately influences gene expression by activating the transcription factor cyclic AMP response element binding protein via phosphorylation. There is evidence that this cAMP-PKA-CREB system is disturbed in depression and that an increased cyclic AMP response element binding protein activity may result in an improved neural plasticity, which in turn could contribute to amelioration of the clinical symptoms of depression.

Prefrontal-temporal gray matter deficits in bipolar disorder patients with persecutory delusions

OBJECTIVES

Although brain structural deficits have been repeatedly associated with bipolar disorder (BD), inconsistency in morphometric results has been a feature of neuroimaging studies. We hypothesize that this discrepancy is related to the heterogeneity of BD, and examine the question of whether or not more homogeneous clinical subgroups display a more coherent pattern of morphometric abnormalities.

METHODS

In a case-control design, we examined differences in gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) concentration in 42 BD patients and 42 healthy matched controls using optimized voxel-based morphometry (VBM). Subgroup analyses of patients with a lifetime history of psychotic symptoms (BDP, n=30) and patients with mood-incongruent psychotic symptoms in the form of persecutory delusions (BDPD, n=15) were performed to accord with previous genetic findings.

RESULTS

Analysis of the total BD sample was largely inconclusive, but the BDPD patient subgroup displayed a widespread pattern of significant decreases in GM concentration in the dorsolateral prefrontal (DLPFC), temporal and cingulate cortices, and a significant CSF increase in the adjacent outer ventricular sulci. Comparison of BDPD patients versus BD and BDP patients without persecutory delusions revealed a significant GM decrease in the left DLPFC for the former group.

CONCLUSIONS

BDPD show pronounced structural abnormalities of the prefrontal and temporal lobes which are similar to the deficits previously reported for schizophrenia (SCZ). Our findings suggest that stratification based solely on psychotic symptoms is insufficient for the differentiation of BD into biologically meaningful subgroups, but also question the pathophysiological validity of the dichotomy in classification between schizophrenia and BD.

Gene expression of NMDA receptor subunits in the cerebellum of elderly patients with schizophrenia

To determine if NMDA receptor alterations are present in the cerebellum in schizophrenia, we measured NMDA receptor binding and gene expression of the NMDA receptor subunits in a post-mortem study of elderly patients with schizophrenia and non-affected subjects. Furthermore, we assessed influence of genetic variation in the candidate gene neuregulin-1 (NRG1) on the expression of the NMDA receptor in an exploratory study. Post-mortem samples from the cerebellar cortex of ten schizophrenic patients were compared with nine normal subjects. We investigated NMDA receptor binding by receptor autoradiography and gene expression of the NMDA receptor subunits NR1, NR2A, NR2B, NR2C and NR2D by in situ hybridization. For the genetic study, we genotyped the NRG1 polymorphism rs35753505 (SNP8NRG221533). Additionally, we treated rats with the antipsychotics haloperidol or clozapine and assessed cerebellar NMDA receptor binding and gene expression of subunits to examine the effects of antipsychotic treatment. Gene expression of the NR2D subunit was increased in the right cerebellum of schizophrenic patients compared to controls. Individuals carrying at least one C allele of rs35753505 (SNP8NRG221533) showed decreased expression of the NR2C subunit in the right cerebellum, compared to individuals homozygous for the T allele. Correlation with medication parameters and the animal model revealed no treatment effects. In conclusion, increased NR2D expression results in a hyperexcitable NMDA receptor suggesting an adaptive effect due to receptor hypofunction. The decreased NR2C expression in NRG1 risk variant may cause a deficit in NMDA receptor function. This supports the hypothesis of an abnormal glutamatergic neurotransmission in the right cerebellum in the pathophysiology of schizophrenia.

Increased D-amino acid oxidase expression in the bilateral hippocampal CA4 of schizophrenic patients: a post-mortem study

An important risk gene in schizophrenia is d-amino acid oxidase (DAAO). To establish if expression of DAAO is altered in cortical, hippocampal or thalamic regions of schizophrenia patients, we measured gene expression of DAAO in a post-mortem study of elderly patients with schizophrenia and non-affected controls in both hemispheres differentiating between gray and white matter. We compared cerebral post-mortem samples (granular frontal cortex BA9, middle frontal cortex BA46, superior temporal cortex BA22, entorhinal cortex BA28, sensoric cortex BA1–3, hippocampus (CA4), mediodorsal nucleus of the thalamus) from 10 schizophrenia patients to 13 normal subjects investigating gene expression of DAAO in the gray and white matter of both hemispheres of the above-mentioned brain regions by in situ-hybridization. We found increased expression of DAAO-mRNA in the hippocampal CA4 of schizophrenic patients. Compared to the control group, both hemispheres of the hippocampus of schizophrenic patients showed an increased expression of 46% (right, P = 0.013) and 54% (left, P = 0.019), respectively. None of the other regions examined showed statistically significant differences in DAAO expression. This post-mortem study demonstrated increased gene expression of DAAO in the left and right hippocampus of schizophrenia patients. This increased expression could be responsible for a decrease in local d-serine levels leading to a NMDA-receptor hypofunction that is hypothesized to play a major role in the pathophysiology of schizophrenia. However, our study group was small and results should be verified using larger samples.

Reduced expression of glutamate transporters vGluT1, EAAT2 and EAAT4 in learned helpless rats, an animal model of depression

BACKGROUND

It has been widely accepted that glial pathology and disturbed synaptic transmission contribute to the neurobiology of depression. Apart from monoaminergic alterations, an influence of glutamatergic signal transduction has been reported. Therefore, gene expression of glutamate transporters that strictly control synaptic glutamate concentrations have to be assessed in animal models of stress and depression.

METHODS

We performed in situ-hybridizations in learned helplessness rats, a well established animal model of depression, to assess vGluT1 and EAAT1-4. Sprague-Dawley rats of two inbred lines were tested for helpless behavior and grouped into three cohorts according to the number of failures to stop foot shock currents by lever pressing.

RESULTS

Helpless animals showed a significantly suppressed expression of the glial glutamate transporter EAAT2 (rodent nomenclature GLT1) in hippocampus and cerebral cortex compared to littermates with low failure rate and not helpless animals. This finding was validated on protein level using immunohistochemistry. Additionally, expression levels of EAAT4 and the vesicular transporter vGluT1 were reduced in helpless animals. In contrast, the transcript levels of EAAT1 (GLAST) and EAAT3 (EAAC1) were not significantly altered.

CONCLUSIONS

These results strongly suggest reduced astroglial glutamate uptake and implicate increased glutamate levels in learned helplessness. The findings are in concert with antidepressant effects of NMDA-receptor antagonists and the hypotheses that impaired astroglial functions contribute to the pathogenesis of affective disorders.

Neuregulin 1 ICE-single nucleotide polymorphism in first episode schizophrenia correlates with cerebral activation in fronto-temporal areas

The Neuregulin (NRG1) gene has been associated with schizophrenia, but its functional implications are largely unknown. Our aim was to assess differential brain activation between patients carrying an at-risk allele on the Neuregulin 1 gene and patients without this genetic risk. Neural signal changes between 14 first episode schizophrenia patients with the at risk allele (SNP8NRG221533) from the Icelandic core haplotype and 14 without were measured with fMRI during a working memory task. Patients without the at risk allele showed greater activations (P < 0.05; corrected) in the left hippocampus, precuneus and cerebellum, as well as the right anterior cingulate. Brain regions previously associated with the pathology of Schizophrenia are differentially affected in those with a genetic at risk status in the NRG1 gene. Heterogeneity of structural and functional measures within patients characterized by clinical phenotypes may be in part due to this genetic variation.

Association of SORL1 gene variants with Alzheimer's disease

SORL1 gene variants were described as risk factor of Alzheimer's disease (AD) additionally SORL1 gene variants were associated with altered Abeta(42) CSF levels in AD patients. In the present study we investigated the association of SORL1 gene variants (rs2070045 (SNP19), SORL1-18ex26 (SNP21), rs3824968 (SNP23), rs1010159 (SNP25)) with AD risk by using Cox proportional hazard model and Kaplan-Meier survival analysis in 349 AD patients and 483 controls, recruited from a multicenter study of the German Competence Network Dementias. The SNP21G-allele and a SORL1 haplotype consisting of the SNP19 T-allele, SNP21 G-allele and SNP23 A-allele (T/G/A) were associated with increased hazard ratios and an earlier age at onset of AD (SNP21: p=0.002; T/G/A haplotype: p=0.007). This effect was most pronounced in carriers of an additional APOE4 allele (SNP21: p=0.003; T/G/A haplotype: p=0.005). In conclusion, we found SORL1 gene variants located in the 3' region of the gene to be associated with increased AD risk and an earlier age at onset of AD in our Central-European population. Thus, our data support a role of SORL1 polymorphisms in AD.

Behavioural alterations in rats following neonatal hypoxia and effects of clozapine: implications for schizophrenia

INTRODUCTION

As a consequence of obstetric complications hypoxia has been discussed as a possible factor in the pathophysiology of schizophrenia. The present study investigated the effects of weak chronic neonatal hypoxia in rats on different behavioural animal models of schizophrenia.

METHODS

(1) After neonatal hypoxia, half of the pups were fostered by normally treated nurse animals to control for possible maternal effects. (2) The animals were tested on postnatal days (PD) 36, 86, 120 and 150 by applying three different behavioural tests: prepulse inhibition (PPI), social interaction and recognition, and motor activity in an open field. (3) Before the PD 150 test, half of the animals had been chronically treated with the antipsychotic drug clozapine (45 mg/kg/day).

RESULTS

Rats exposed to hypoxia as neonates exhibited a deficit in locomotor activity on PD 86, 120, and 150, as well as a PPI deficit on PD 120 and 150 but not before. Chronic treatment with clozapine reverses the hypoxia induced PPI deficit, but not the decreased locomotor activity. In a second experiment, clozapine was chronically administered before PD 120 and blocked the development of the PPI deficit in the animals exposed to hypoxia.

DISCUSSION

The time course of the hypoxia-induced PPI deficit and reversibility by clozapine supports the validity of our animal model and the hypothesis that hypoxia as an obstetric complication is an important factor in the pathophysiology of schizophrenia.

Abnormal amygdala activation profile in pedophilia

Despite considerable public interest research in neurobiological correlates of pedophilia is scarce. Since amygdala activation is central for emotional valuation, arousal, and salience, we investigated the activation profile of this structure in 10 male subjects with pedophilia (exclusively attracted to boys), all convicted sex-offenders and sentenced to forensic psychiatric treatment along with ten male heterosexual matched controls. We used a sexually non-explicit functional Magnetic Resonance Imaging (fMRI) paradigm with images of men, women, boys or girls randomly embedded in neutral target/non-target geometrical symbols. We applied statistical parametric mapping (SPM2) and SPSS 14 for image processing and analysis. While controls activated significantly less to pictures of children compared to adults, the activation profile was reversed in subjects with pedophilia, who exhibited significantly more activation to children than adults. The highest activation was observed for boys in the patient group, and for women in control participants. Our data show enhanced activation to children's pictures even in an incidental context and suggest the provocative hypothesis that a normally present mechanism for reduced emotional arousal for children relative to adults is reversed in pedophilia, suggesting a neural substrate associated with deviant sexual preference in this condition. More extensive research in this field would be of benefit for both the victims and the offenders.

Elevated spectroscopic glutamate/gamma-amino butyric acid in rats bred for learned helplessness

The theory of depression is dominated by the monoamine hypothesis but there is increasing evidence that beyond monoamines, glutamate (Glu) and gamma-aminobutyric acid (GABA) play an essential role in the pathogenesis of depression. In this study, the effect of alterations of GABA and Glu were investigated in the congenital learned helplessness paradigm. Proton magnetic resonance spectroscopy is an important monitoring tool to bridge the findings in clinical and preclinical studies. We found increased Glu/GABA ratios in the hippocampus and prefrontal cortex of placebo-treated (saline intraperitoneally) congenital learned helplessness rats versus wild-type rats, and a treatment-induced (desipramine 10 mg/kg intraperitoneally or electroconvulsive shock) decrease of this monoamine ratio in both brain regions. Our results corroborate previous findings of an amino-acid influence on the pathomechanisms of mood disorders.

Neurogenesis and depression: what animal models tell us about the link

There is growing evidence that stress causes a decrease of neurogenesis in the dentate gyrus and antidepressant treatment in turn stimulates the cell proliferation in the dentate gyrus. This has led to the hypothesis that a decreased neurogenesis might be linked to the pathophysiology of major depression. The article reviews the relationship of depressive-like behavior and neurogenesis in three animal models of depression with high validity: learned helplessness, chronic mild stress and chronic psychosocial stress of the tree shrew. All animal models provide evidence that stress which can lead to depressive-like behavior, in parallel causes a decrease of neurogenesis; vice versa, antidepressant treatment is able to revert not only behavioral changes but also to normalize neurogenesis. But the animal models argue against the notion that decreases of neurogenesis are the cause or the consequence of depressive-like behavior since depressive-like behavior can occur without impairments in neurogenesis and decreasing neurogenesis does not neccessarily lead to depressive-like behavior. This suggests that neurogenesis does not directly control affect but is tightly connected to the modulation of affect by stress and antidepressant measures.

Tissue-sparing effect of x-ray microplanar beams particularly in the CNS: is a bystander effect involved?

OBJECTIVE

Normal tissues, including the central nervous system, tolerate single exposures to narrow planes of synchrotron-generated x-rays (microplanar beams; microbeams) up to several hundred Gy. The repairs apparently involve the microvasculature and the glial system. We evaluate a hypothesis on the involvement of bystander effects in these repairs.

METHODS

Confluent cultures of bovine aortic endothelial cells were irradiated with three parallel 27-microm microbeams at 24 Gy. Rats' spinal cords were transaxially irradiated with a single microplanar beam, 270 microm thick, at 750 Gy; the dose distribution in tissue was calculated.

RESULTS

Within 6 hours following irradiation of the cell culture the hit cells died, apparently by apoptosis, were lost, and the confluency was maintained. The spinal cord study revealed a loss of oligodendrocytes, astrocytes, and myelin in 2 weeks, but by 3 months repopulation and remyelination was nearly complete. Monte Carlo simulations showed that the microbeam dose fell from the peak's 80% to 20% in 9 microm.

CONCLUSIONS

In both studies the repair processes could have involved "beneficial" bystander effects leading to tissue restoration, most likely through the release of growth factors, such as cytokines, and the initiation of cell-signaling cascades. In cell culture these events could have promoted fast disappearance of the hit cells and fast structural response of the surviving neighboring cells, while in the spinal cord study similar events could have been promoting angiogenesis to replace damaged capillary blood vessels, and proliferation, migration, and differentiation of the progenitor glial cells to produce new, mature, and functional glial cells.

Reduced expression of complexins I and II in rats bred for learned helplessness

Disturbed synaptic transmission contributes to the pathophysiology of mood disorders. Post mortem studies reported reduced expression of the synaptic vesicle protein (SVP) complexins I and II in depression. Antidepressants were found to induce the expression of these genes. Since animals with congenital susceptibility to learned helplessness provide a valid animal model of depression, we investigated the expression of different SVPs in this system by semiquantitative in situ hybridization. Rats bred for congenital learned helpless behavior (cLH, N=6) failed to interrupt foot shock currents by lever pressing (mean 12.3 failures out of 15 trials). These animals showed significantly lower expression of complexins I and II mRNA in hippocampal, limbic and cortical brain areas compared to not helpless animals (cNLH, N=6) with a mean failure rate of 0.83 out of 15 trials. Expression levels of complexins I and II significantly correlated with the failure rate in the test paradigm. In contrast, the expressions of synaptotagmin I and synaptophysin were found unchanged. This investigation provides a further validation of the LH model of depression. The experimental data fit well into current pathogenetic concepts of mood disorders and support the hypothesis, that complexins are pivotal players in the pathophysiology of depression and tentative targets of antidepressants.

Correlation between MR-spectroscopic rat hippocampal choline levels and phospholipase A2

Hippocampal choline-containing compounds (Cho) determined with 1H MR spectroscopy (MRS) are decreased in major depression episodes and return to baseline levels after antidepressive electroconvulsive therapy (ECT). A rise in hippocampal Cho has been observed in rats upon electroconvulsive shocks (ECS), an analogue of human ECT. Choline production involves the activity of various phospholipases. In order to investigate whether the increase of Cho correlates with an enhanced expression of phosphoslipase A2 (PLA2) we took rectangular tissue samples from the region of the MRS voxel for immunoblotting. Our data show a significant inverse correlation (p = 0.018) between PLA2 protein levels and MRS Cho/NAA levels suggesting a possible downregulation of PLA2 in compensation for an upregulation of other phospholipases.

Subcortical and medial temporal MR-detectable metabolite abnormalities in unipolar major depression

The purpose of the present study was to determine whether MR-detectable alterations of choline-containing compounds in two key neural systems involved in major depression disorder namely the hippocampus and the basal ganglia can be detected. Multislice proton magnetic resonance spectroscopic imaging was applied in 11 patients with major depressive disorder (MDD) and ten matched healthy subjects. Voxels were selected from the left and right side of the hippocampus and the putamen. Significantly lower choline-containing compounds in the hippocampus and significantly higher choline-containing compounds in the putamen of patients with MDD compared to healthy subjects were found. No significant differences were found for the other metabolites in the two regions evaluated. Abnormal levels of choline-containing compounds most likely reflect altered membrane phospholipid metabolism. A reduced level in the hippocampus and an increased level in the putamen suggest regionally opponent membrane abnormalities.

Neural correlates of working memory dysfunction in first-episode schizophrenia patients: an fMRI multi-center study

Working memory dysfunction is a prominent impairment in patients with schizophrenia. Our aim was to determine cerebral dysfunctions by means of functional magnetic resonance imaging (fMRI) in a large sample of first-episode schizophrenia patients during a working memory task. 75 first-episode schizophrenia patients and 81 control subjects, recruited within a multi-center study, performed 2- and 0-back tasks while brain activation was measured with fMRI. In order to guarantee comparability between data quality from different scanners, we developed and adopted a standardized, fully automated quality assurance of scanner hard- and software as well as a measure for in vivo data quality. After these quality-control measures had been implemented, 48 patients and 57 controls were included in the final analysis. During attention-related processes, even when the performance between patients and controls was comparable, there was a recognizable emergence of cerebral dysfunctions with hypoactivations in the ventrolateral prefrontal cortex (VLPFC), in the superior temporal cortex and in the thalamus. During working memory performance, parietal hypoactivations, especially in the precuneus, were prominent and were accompanied by poorer performance in patients. A hyperfrontality emerged in the ventrolateral prefrontal cortex. Hence, results point to a dysfunctional ventrolateral prefrontal-parietal network during working memory in patients, suggesting impairments in basic functions such as retrieval, storage and maintenance. The brain activation pattern of this large and significant sample of first-episode schizophrenia patients indicates an imbalanced system failing to adjust the amount of brain activity required in the cerebral network involved in attention and working memory.

D2 antidopaminergic modulation of frontal lobe function in healthy human subjects

BACKGROUND

Although the major principles of dopamine (DA) signaling have been well described previously, its precise modulatory impact on the prefrontal cortex (PFC) in humans is poorly understood. Two major neurophysiological models propose segregated functional circuits on the systems level as well as D(1) and D(2) receptor-dependent processing states on the cellular level (two-state model).

METHODS

We examined the predictive validity of these models in 10 healthy male volunteers with a haloperidol challenge (HLP). Cortico-striatal-thalamo-cortical (CSTC) motor loop functions were examined during functional magnetic resonance imaging (fMRI) with a sequential finger opposition task. Neuropsychological implications of the two-state model were evaluated with a test battery of D(1)- or D(2)-sensitive prefrontal measures.

RESULTS

Analysis of fMRI data revealed a significant HLP-induced blood oxygen level dependent-signal decrease in the sensorimotor striatum and a lateralized activation loss of ipsilateral higher order motor cortices and contralateral cerebellum. Neuropsychological evaluation demonstrated a preferential impairment of D(2)-sensitive functions, whereas D(1) or non-dopaminergic domains were unaffected.

CONCLUSIONS

Our data support the hypothesis that mesocortical D(1) and D(2) receptors exert differential influences in the PFC for cognitive function, but the nigrostriatal CSTC network model for the motor domain could not be confirmed.

ECT Anesthesia: The Lighter the Better?

BACKGROUND

Electroconvulsive therapy (ECT) is a most effective treatment for patients with major affective disorders. The influence of anesthetic drugs on seizure "adequacy" or on treatment success has not been systematically investigated.

METHODS

A bispectral EEG index score (BIS) was used to identify the depth of anesthesia during ECT. Our study included 22 major depressive episode (MDE) patients expanding to 219 ECTs (05/05-01/06) with no limitations of concurrent medication.

RESULTS

Fourteen out of the 22 patients showed full remission. Individual number of ECT sessions needed to reach full remission correlated negatively with mean pre-ECT BIS values (p=0.001). Additionally, using a repeated measurement regression analysis significant correlations were found for pre-ECT BIS versus motor response time, seizure concordance, ictal coherence and peak heart rate.

CONCLUSION

The results of our study suggest BIS-levels as a predictor of faster ECT response. Controlling BIS-levels before stimulation may have an additional effect on treatment success.

Altered NMDA receptor expression and behavior following postnatal hypoxia: potential relevance to schizophrenia

The present study investigated the effects of chronic, repeated hypoxia during a postnatal vulnerable period. Acoustic startle response in adult rats was measured along with NMDA receptor binding and mRNA expression of subunits at postnatal days (PND) 11 and 120. Rats at PND 120 exhibited a deficit in prepulse inhibition of acoustic startle response. In PND 11 rats, chronic hypoxia decreased NMDA receptor binding and increased transcript expression of NR1 subunit in frontal and temporal regions, nucleus accumbens and hippocampus, while NR2A subunit expression was downregulated in hippocampal subregions. At PND 120, gene expression of NR1 was still increased in hippocampal, frontal and temporal subregions as well as nucleus accumbens. A prepulse inhibition deficit points to schizophrenia-like behavior in adult (PND 120) rats. Compensatory upregulation of NR1 expression may occur due to NMDA receptor hypofunction. We discuss this animal model to further analyze effects of hypoxia as a factor of obstetric complications in the pathophysiology of schizophrenia.

Alcohol consumption significantly influences the MR signal of frontal choline-containing compounds

The aim of this work was to evaluate the relationship between the amount of alcohol consumption of a group of social drinkers and the magnetic resonance spectroscopy signal of choline-containing compounds (Cho) in the frontal lobe. Two independent long echo (TE = 135 ms) (1)H MRSI studies, the first comprising 24 subjects with very low alcohol consumption, the second 18 subjects with a more widespread alcohol consumption were conducted. Significant correlations of Cho measures from frontal white matter and from the anterior cingulate gyrus with alcohol consumption in the last 90 days prior to the MR examination were found. Age, gender, and smoking did not show significant effects on the metabolite measures. Partialling out the effect of the voxel white matter content did not change the correlation of choline measures with alcohol consumption. The main conclusion from the repeated finding of a positive correlation of alcohol consumption and frontal Cho signals is that monitoring for alcohol consumption is mandatory in MRS studies where pathology depended Cho changes are hypothesized.

[Continuation ECT]

A renaissance of electroconvulsive therapy in psychiatry can be observed in Germany. Here, ECT was named as a first line therapy for treating psychotic depression, depressive stupor, schizoaffective psychoses with severe depressive symptoms. Suprisingly, ECT is most commonly not used as a continuation therapy after achieving acute remission. With rare exceptions, antidepressive medication is chosen for this purpose. The use of continuation ECT (cECT) and subsequent maintenance ECT (mECT) is not (or just marginally) mentioned in practice guidelines. In our case report we report a successful cECT and mECT of a geriatric patient with severe comorbidity. This case is exemplified with respect to recent guidelines and study results. Particularly suggestions for interval duration, total duration of treatment, effects on cognition and memory, comorbidity and comedication, and reflections on quality of life and costs were discussed. We would therefore recommend a broader use of this proven treatment tool for keeping major depressions in remission.

Mice with genetically altered glucocorticoid receptor expression show altered sensitivity for stress-induced depressive reactions

Altered glucocorticoid receptor (GR) signaling is a postulated mechanism for the pathogenesis of major depression. To mimic the human situation of altered GR function claimed for depression, we generated mouse strains that underexpress or overexpress GR, but maintain the regulatory genetic context controlling the GR gene. To achieve this goal, we used the following: (1) GR-heterozygous mutant mice (GR+/-) with a 50% GR gene dose reduction, and (2) mice overexpressing GR by a yeast artificial chromosome resulting in a twofold gene dose elevation. GR+/- mice exhibit normal baseline behaviors but demonstrate increased helplessness after stress exposure, a behavioral correlate of depression in mice. Similar to depressed patients, GR+/- mice have a disinhibited hypothalamic-pituitary-adrenal (HPA) system and a pathological dexamethasone/corticotropin-releasing hormone test. Thus, they represent a murine depression model with good face and construct validity. Overexpression of GR in mice evokes reduced helplessness after stress exposure, and an enhanced HPA system feedback regulation. Therefore, they may represent a model for a stress-resistant strain. These mouse models can now be used to study biological changes underlying the pathogenesis of depressive disorders. As a first potential molecular correlate for such changes, we identified a downregulation of BDNF protein content in the hippocampus of GR+/- mice, which is in agreement with the so-called neurotrophin hypothesis of depression.

Increased serum S100B in elderly, chronic schizophrenic patients: negative correlation with deficit symptoms

In schizophrenia, elevations of serum and CSF S100B levels have been reported and related to state of the disease and negative symptoms. In elderly chronic schizophrenic inpatients with stable medication, S100B may be increased and correlated to psychopathology and neuropsychological deficits. We have measured serum levels of S100B in 41 elderly, chronic schizophrenic patients and 23 age- and gender-matched controls using an immunoluminometric assay. In patients, we assessed detailed psychopathology and neuropsychological performance and determined serum levels of haloperidol, clozapine and its two main metabolites desmethylclozapine and clozapine metabolite N-oxid by HPLC. S100B levels were increased in elderly chronic schizophrenic patients compared to healthy controls. In patients, levels were negatively correlated with deficit symptoms and positively with age. There were no significant differences of S100B between medication groups and no correlation with serum levels of antipsychotics or neuropsychological scores. Elevations of S100B in elderly chronic schizophrenic patients may be related to an active disease process lasting until old-age. Correlations point to the impact of S100B in neuroplasticity and ageing. Post-mortem studies should clarify the presence of altered S100B function in the brain and its relationship to neuroplastic or neurodegenerative processes.

Lithium and ECT--concurrent use still demands attention: three case reports

Bipolar disorders as well as recurrent major depressive episodes can be most effectively treated with electroconvulsive therapy (ECT). Since continuation/maintenance ECT is not well established, prophylactic therapy in recurrent illnesses is more commonly carried out using antidepressive medication alone or more often in combination with lithium. In case of relapse the clinically important question of discontinuation of lithium versus the concurrent use of ECT and lithium may arise. The safety of concurrent use has also to be balanced when lithium treatment is started within an ECT course. Since recent studies have reported no negative interactions with concurrent use, we here report three cases (one case of a prolonged seizure, a serotonin syndrome and a focal seizure) of severe lithium-induced side effects while patients underwent ECT without complications and lithium serum levels were still subtherapeutic. Clinical consequences are discussed and disturbances of the blood brain barrier system as a speculative cause are hypothesized taking previous studies, animal studies and an additional reported clinical case into account.

Erhaltungselektrokrampftherapie bei depressiven Störungen

Nowadays, electroconvulsive therapy (ECT) is undergoing a renaissance in psychiatry: it is now considered a first-line therapy for treating psychotic depression or other disorders with severe depressive symptoms. Surprisingly, ECT is most commonly not used as continuation therapy after acute remission. With rare exceptions, antidepressive medication is chosen for this purpose. The use of continuation ECT (cECT) and subsequent maintenance ECT (mECT) is not or just marginally mentioned in practice guidelines. In this article, we suggest guidelines for cECT, taking therapy recommendations and recent studies into account. Particularly, indication, management, comedication and comorbidity, side effects, and costs are examined. Today, cECT is underindicated as a result of assumed problems, fears, and stigmas. We would therefore recommend broader use of this proven treatment tool for keeping major depression in remission.

Genotype-phenotype studies in bipolar disorder showing association between the DAOA/G30 locus and persecutory delusions: a first step toward a molecular genetic classification of psychiatric phenotypes

OBJECTIVE

The authors previously reported an association between the D-amino acid oxidase activator (DAOA)/G30 locus and both schizophrenia and bipolar affective disorder. Given the presumed role of DAOA/G30 in the neurochemistry of psychosis and its localization in a schizophrenia and bipolar affective disorder linkage region (13q34), it was hypothesized that the bipolar affective disorder finding would be mainly due to an association with psychotic features.

METHOD

The marker/haplotype associations obtained in a subset of 173 bipolar affective disorder patients with psychotic features were similar to those in the overall patient group, suggesting that stratification on the basis of psychotic features in general might be too crude a procedure. The authors therefore tested whether confining caseness to specific psychotic features would improve detection of genotype-phenotype correlations.

RESULTS

In a logistic regression, "persecutory delusions" were found to be the only significant explanatory variable for the DAOA/G30 risk genotype among 21 OPCRIT symptoms of psychosis. The authors therefore tested for association between DAOA/G30 and bipolar affective disorder in the 90 cases with a history of persecutory delusions. Whereas this subset showed strong association (odds ratio=1.83 for the best marker), the remaining larger sample of 165 patients with no such history did not differ from comparison subjects, suggesting that the association between DAOA/G30 and bipolar affective disorder is due to persecutory delusions. This was confirmed in an independent study of 294 bipolar affective disorder patients and 311 comparison subjects from Poland, in which an association between bipolar affective disorder and DAOA/G30 was only seen when case definition was restricted to cases with persecutory delusions.

CONCLUSIONS

These data suggest that bipolar affective disorder with persecutory delusions constitutes a distinct subgroup of bipolar affective disorder that overlaps with schizophrenia.

[One decade of functional imaging in schizophrenia research. From visualisation of basic information processing steps to molecular-genetic oriented imaging]

Modern neuroimaging techniques such as magnetic resonance imaging (MRI) and positron emission tomography (PET) have contributed tremendously to our current understanding of psychiatric disorders in the context of functional, biochemical and microstructural alterations of the brain. Since the mid-nineties, functional MRI has provided major insights into the neurobiological correlates of signs and symptoms in schizophrenia. The current paper reviews important fMRI studies of the past decade in the domains of motor, visual, auditory, attentional and working memory function. Special emphasis is given to new methodological approaches, such as the visualisation of medication effects and the functional characterisation of risk genes.

Antidepressants differentially affect expression of complexin I and II RNA in rat hippocampus

Disturbance of synaptic transmission is currently viewed as an important pathophysiological mechanism and therapeutic target of mood disorders. Amongst other lines of evidence this theory is based on human post-mortem investigations showing differential expression of complexins. In order to discriminate between molecular correlates of the disease itself and effects of psychotropic drugs given to patients, we performed an animal trial using subchronic antidepressant treatment. Cohorts of adult male Sprague-Dawley rats were treated over a period of 14 days with intraperitoneal injections of either saline (0.9%, n=8), desipramine (15 mg/kg, n=7), fluoxetine (10 mg/kg, n=8), or tranylcypromine (10 mg/kg, n=5). Brain slices were used for in situ hybridizations with 35S labelled RNA probes of the genes complexin I, complexin II and syntaxin 1 A, the SNARE complex protein interacting with the complexins, and assessed semi-quantitatively for region-specific expression levels. Expression of complexin I was induced only in habenular nuclei after treatment with fluoxetine. In contrast, complexin II was significantly induced by desipramine and tranylcypromine, but not fluoxetine, in several brain regions. All treatment groups, but most significantly fluoxetine-treated animals, showed higher expression levels of syntaxin 1A. Antidepressants differentially affect expression levels of complexin I and more prominently complexin II and syntaxin 1A. The induction of complexin II and syntaxin 1A might strengthen the synaptic transmission at axo-dendritic or axo-axonal synapses. Previous post-mortem findings reporting on downregulation of complexins cannot be explained as mere effects of psychotropic drug treatment.

Reduced sensitivity to sucrose in rats bred for helplessness: a study using the matching law

Anhedonia is a core symptom of depression. As it cannot be directly assessed in rodents, anhedonia is usually inferred from a reduced consumption of, or preference for, a reinforcer. In the present study we tried to improve the measurement of anhedonia by performing a detailed preference analysis based on the generalized matching law and tested its sensitivity in rats congenitally prone (cLH) or resistant (cNLH) to learned helplessness. According to the current interpretation of learned helplessness as a model for depression, a reduction in the rewarding properties of sucrose in cLH rats was hypothesized. Our results revealed that the 'preference allocation' index provided by this test, but not the traditional measures of sucrose consumption or preference over water, was significantly lower in cLH rats, and was correlated with the helpless behaviour as measured in an escape procedure. Therefore, it is clear that more subtle preference measures provided by the analysis of choice using the matching law principles are more sensitive and discriminative than those based on consumption of, or preference for, a single concentration of sucrose over water. Moreover, our data are in agreement with the proposed relationship between helplessness and sucrose preference, and support the usefulness of the cLH and cNLH rats as a model of depression.

Further evidence for altered cerebellar neuronal integrity in schizophrenia

OBJECTIVE

The authors' goal was to investigate the distribution of metabolites and voxel composition in the pons and three cerebellar subregions and compare metabolite integral values and differences in voxel composition between patients with schizophrenia and healthy subjects.

METHOD

Proton magnetic resonance spectroscopic imaging was used to study the cerebellum and pons of 14 patients with schizophrenia and 14 healthy comparison subjects.

RESULTS

The voxel composition was not significantly different between the groups, but the patients with schizophrenia had significantly lower N-acetylaspartate levels in the cerebellar cortex and vermis.

CONCLUSIONS

The lower integral value of N-acetylaspartate in the cerebellar cortex and the vermis of patients with schizophrenia supports the theory of a dysfunctional corticocerebellar-thalamic-cortical circuit in schizophrenia.

Voluntary alcohol intake in two rat lines selectively bred for learned helpless and non-helpless behavior

RATIONALE

A high comorbidity between depression and alcoholism has been reported in several studies, but the mechanisms underlying this relationship remain unknown.

OBJECTIVES

We tested whether learned helplessness in rats as a model for depression is associated with enhanced alcohol intake and relapse behavior.

METHODS

Congenital learned helplessness (cLH) and congenital non-learned helplessness (cNLH) rats were selectively bred for differences in an escape paradigm. Sucrose preference was tested at the first hour of the dark phase. In order to study an association with alcohol drinking behavior, rats underwent a free-choice procedure with access to water, and 5% and 20% alcohol solutions for 6 weeks. After acquisition of alcohol drinking behavior, the alcohol deprivation effect (ADE) was assessed. Sensitivity to the sedative-hypnotic effect of alcohol was measured by loss of the righting reflex.

RESULTS

cLH rats showed significantly lower preference for sucrose solutions during the second half hour of the dark phase than cNLH rats. Alcohol intake of male cLH rats was not significantly different from that of male cNLH rats. In contrast, cLH female rats consumed higher amounts of alcohol than female cNLH rats. The ADE was more pronounced in female animals, although the magnitude of the ADE was similar in both cNLH and cLH female rats. The time to regain the righting reflex was significantly higher in both male and female cLH rats than in cNLH rats.

CONCLUSIONS

In summary, these data suggest that an inborn depressive-like behavior in female rats is associated with enhanced alcohol intake.

Ethanol induces expression of the glutamate transporters EAAT1 and EAAT2 in organotypic cortical slice cultures

BACKGROUND

Exposure of the developing brain to ethanol disposes the fetus to fetal alcohol syndrome and causes a number of changes in several neurochemical systems. In particular, the glutamatergic system is affected by ethanol. Thus, increased sensitivity of glutamate receptors and enhanced transmembrane transport of glutamate were found in primary astrocyte cultures. However, in these in vitro studies, changes in the expression of glutamate transporters were not detected. To further characterize the influence of chronic ethanol exposure on the developing brain, we assessed the transcriptional and translational regulation of glutamate transporters in a less artificial in vitro system.

METHODS

We exposed postnatal rat cortical organotypic slice cultures to ethanol (100 mM) for 4 and 8 days. Expression of the excitatory amino acid transporters EAAT1 and EAAT2 was analyzed in comparison to untreated controls with semiquantitative reverse transcriptase-polymerase chain reaction. In addition, changes in protein expression were detected by Western blotting.

RESULTS

In ethanol-exposed cortical slices, we observed more prominent fiber outgrowth and significantly increased gene expression (EAAT1: +35%, p = 0.029; EAAT2: +251%, p = 0.015). These findings could be verified on the protein level, because Western blot analysis revealed significantly higher levels of EAAT1 (+76%; p = 0.008) and EAAT2 (+104%; p = 0.018) in ethanol-treated slices compared with controls.

CONCLUSIONS

Our results are in concert with earlier studies describing the induction of glutamate transport by ethanol. Enhanced expression of EAAT1 and EAAT2 after ethanol exposure can be viewed as a maladaptive process that disposes the developing brain to fetal alcohol syndrome.